A new flowtube reactor employing dissociative electron attachment to produce radicals and high-pressure photoionization in the mass spectrometric detection of radicals is described. The system has been applied to a study of the association reactions of CHClz and CCl3 with 0 2 in a great excess of helium at total densities below 1017 cm-3 over the temperature range 286 to 332 K. Both reactions display a strong negative temperature coefficient. The results can be parameterized in the form ko(CHC12 + 0 2 ) = (4.3 ? 0.2) x 10-31(T/300)-6.7'0.7 cm6 s-', ko(CC1S + 0 2 ) = (2.7 ? 0.2) X 10-31(T/300)-8.7'1.0 cm6 5 -l .
We consider the polymerization of α-methylstyrene, initiated by sodium naphthalide in the solvent tetrahydrofuran on time scales that permit full thermodynamic equilibrium between the monomer and the polymer. We present new measurements as a function of temperature of the mass density, the shear viscosity, and the liquid–vapor surface tension, and we compare the data to theoretical expectations when the polymerization is viewed as a phase transition. The mass density is well described by either mean field or nonmean field theories. The shear viscosity increases as the average degree of polymerization (DP) increases, but the exponent 3.4 is not reached, presumably because the DP is too small. The surface tension increases as the DP increases, indicating depletion of the polymer from the surface.
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